What my problem sir sir how to receive the preamble and the sync word. In other words, how the receiving part would be able to recognize the pre= amble and sync byte from the data needed to be shown on the LCD. Peter Betts wrote: > My problems are on the preamble, sync word, and the checksum/ > CRC. Basically, it's packet transmission and reception. Preamble's are just a long string of 1's and 0's to indicate transmission= is about to start. Sync words are just a collecting of 1's and 0's in a specific pattern tha= t is long enough for the receiving system to lock onto (correlate) and synchronise at the appropriate bit rate. Checksum is a Cyclic Redundancy Check and is normally a delay line with XOR'ed taps fedback into the delay line input. (The feedback bit gives yo= u the "cyclic" term) There are many many text books that explain CRC generation. It can be as = big or small as you like. If it's a PC you are talking to then I don't know t= he correct polynomial for the CRC in this circumstance. You notice how again you can break this down into smaller and smaller bit= s. If it's a PC you're talking to get the speification of the interface and read it. Then just try a simple terminal program and turn off all fancy handshaking or parity checking. Just try raw data communications. When th= at works try adding CRC (parity) etc etc. Pete -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body ____________________________________________________________________ Get free email and a permanent address at http://www.netaddress.com/?N=3D= 1 -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body